Rotatable cooler for a rotary kiln plant

ABSTRACT

A cooler (6) for cooling of particulate material which is subjected to heat treatment in the rotary kiln is mounted at the material outlet end (1) of a rotary kiln. The cooler is provided with annular chambers (7, 8, 9) disposed around each other, and which are successively passed by the material from the outlet (5) of the kiln to a material outlet (20) in the stationary housing (15) of the cooler in countercurrent with the cooling air which flows from an air inlet (18) and through the annular chambers to the kiln in which the air thus heated is utilized as combustion air.

The invention relates to a rotatable cooler for air cooling ofparticulate material subsequent to its heat treatment in a rotary kiln,the cooler being mounted on the outlet end of the kiln and comprisingseveral chambers which are parallel to the kiln axis and through whichthe material can be conducted in counter-current with the cooling air,said chambers being surrounded by a stationary housing.

Coolers of the above-mentioned kind are known inter alia as so-calledsatellite coolers, for example from the description to British PatentNo. 1365171. Such satellite coolers are very effective for cooling offor example cement clinker after burning and areas of applicationinclude high-capacity plants.

However, a satellite cooler is rather voluminous and expensive tomanufacture and particularly difficult to install on existing kilns notalready equipped with a cooler of this type.

It is the object of the present invention to provide a cooler which isboth economical to manufacture and of a compact design, and which can beinstalled on rotary kilns without any major difficulties.

According to the invention this is achieved by a cooler of the kindmentioned in the introduction, being characterized in that the chambersare annular chambers disposed around each other, being inter-coaxial andcoaxial with the kiln, and fixed to and protruding away from thematerial outlet end of the kiln, that the chambers are divided intolongitudinal ducts by means of partitions and guide vanes for conveyingthe material successively through the annular chambers, that the inletof the innermost annular chamber is connected to the kiln outlet via anannular gap between the cooler housing and the kiln end, that eachchamber placed between the innermost and the outermost annular chamberhas its inlet connected to the outlet of the immediately precedingannular chamber and its outlet connected to the inlet of the immediatelysurrounding annular chamber, and that the material outlet of theoutermost annular chamber is connected to the cooler inlet for coolingair.

The burner for heat treatment of the material in a rotary kiln isnormally fitted in the material outlet end of the kiln. The burner issupplied with combustion air, which is preheated in the cooler, and thisairstream enters through the above-mentioned annular gap, thus ensuringthat the air is effectively distributed around the burner.

Given that the burner is fitted in such a way that it protrudes awayfrom the kiln end, it is possible to support the kiln very close to itsoutlet end and to achieve more effective cooling of this end by theambient air. Further, the condition of the thermal zone of the kiln canbe monitored more effectively, for example by means of infraredmeasurements.

The internally fitted partitions and guide vanes inside the annularchambers provide a wide range of options for discharging thefinish-cooled materials from the cooler, and, therefore, the coolerhousing may have a material outlet which is connected to the materialoutlet of the outermost annular chamber, and which is located at thatpart of the annular chamber being the uppermost at any time.

With the material outlet being placed at such a high level, it ispossible to attain a low building height for the entire kilninstallation and also to obtain space for equipping the material outletof the cooler housing with a material chute having at least one gratefor separating the cooled material into particle size fractions.

In order to disintegrate oversize lumps of material which may get stuckin the annular gap, thus causing stoppage and wear, materialdisintegration means may be fitted in the annular or inlet gap of thecooler.

The inlet for cooling air to the cooler may advantageously be formed byan annular air gap between cooler housing and the outermost annularchamber.

Since the different annular chambers are heated to differenttemperatures, it is advantageous that the annular chambers are connectedto one another and to the housing with due allowance for expansion, forexample by means of sliding guides and laminated seals.

The invention will now be described in further details by means of anembodiment of a cooler according to the invention and with reference tothe accompanying drawing, being diagrammatical, and where

FIG. 1 shows a side view, partly in sectional cut, of a cooler accordingto the invention, and

FIG. 2 shows a section according to the line II--II in FIG. 1

In FIG. 1 is shown the outlet end 1 of a rotary kiln which is supportedvia a live ring 2 on a roller support 3. The material subjected to heattreatment in the kiln is heated by means of a burner 4, whereas thematerial is conveyed through the kiln in known manner and discharged atthe kiln outlet 5.

On the outlet of the kiln is mounted a cooler 6 comprising severalannular chambers, on the drawing three chambers 7, 8, 9, which areindividually separated by means of cylindrical walls 10 and 11. Theannular chambers are divided into longitudinal ducts by means ofpartition walls 12, 13, 14, which also operate as guide vanes. Therotatable annular chambers are surrounded by a stationary housing 15,which, inside the innermost annular chamber 7, is protruding towards thekiln outlet 5 where in conjunction with the latter it forms an annulargap 16, and which together with the outer wall 17 of the outermostannular chamber forms an air inlet gap 18 for supply of cooling air tothe cooler.

The operating principle of the cooler is as follows:

The material to be cooled in the cooler is conveyed from the kiln outlet5, via the annular gap 16, into and through the innermost annularchamber 7 to the outlet 19 of the latter, which outlet simultaneouslyconstitutes the inlet for the intermediate annular chamber 8 and onwardthrough the intermediate annular chamber 8 and the outermost annularchamber 9 from which the material is discharged by means of thepartition walls and the guide vanes 14 through a material outlet 20which is located in the upper section of the cooler housing.

Cooling air is sucked in through the gap 18 between the outermostannular chamber wall 17 and the cooler housing 15 and the air isconveyed, counter-current to the material stream, from the outermost tothe innermost annular chamber and onward via the annular gap 16 into thekiln end, in which the now heated cooling air is utilized as combustionair for the burner 4.

In the material outlet 20 from the cooler housing 15 a grate 21 may befitted at the bottom of the outlet applicable for a separation of thefinish-cooled material according to particle sizes.

Further, as indicated at 22, certain impacting devices may be installedon the rotating kiln end in the annular gap 16, and these devices areused to disintegrate lumps of material which are too large to passthrough the annular gap 16, and which also would reduce the coolingefficiency of the material in the cooler 6.

I claim:
 1. A cooler adapted for being arranged at an outlet end of arotary kiln having a material inlet end and a material outlet end toserve the purpose of air cooling particulate material subsequent to itsheat treatment in the kiln,said cooler comprising annular coaxialchambers communicating to form a path for conducting the particulatematerial through the cooler in counter-current with a cooling airstream, wherein said cooler comprises a stationary portion comprising astationary housing and a rotatable portion surrounded by the stationaryhousing and comprising a set of annular chambers disposed coaxiallyaround each other and adapted for being mounted at the outlet end of thekiln coaxially with the kiln, said cooler being mounted at the outletend of the kiln such that it extends beyond the outlet end and thus doesnot substantially overlap the outer surface of the outlet end, saidannular chambers being divided into longitudinal ducts by means ofpartitions and guide vanes, the set of annular chambers comprising atleast an innermost chamber, an intermediate chamber and an outermostchamber, the innermost chamber having an inlet communicating with thekiln outlet through an annular gap between the stationary housing andthe kiln outlet end, in that each duct within the intermediate chamberhas an inlet communicating with the outlet of a duct within theimmediately preceding annular chamber and an outlet communicating withan inlet of the immediately surrounding outermost chamber to form a pathfor conveying the material successively through the annular chambers,and in that the outermost chamber comprises an inlet for theintroduction of cooling air.
 2. A cooler according to claim 1, whereinthe stationary housing has a material outlet (20) in the upper sectionof the stationary housing which is connected to the material outlet ofthe outermost annular chamber (9) so that material may be dischargedfrom that part of the annular chamber which the uppermost one at anytime.
 3. A cooler according to claim 2, wherein the material outlet (20)of the cooler housing comprises a material chute having at least onegrate (21) for separating the cooled material into particle sizefractions.
 4. A cooler according to claim 1, wherein materialdisintegration means (22) are fitted in the annular gap (16) of thecooler (6).
 5. A cooler according to any one of the preceding claims,whereinin the cooling air inlet is formed by an annular air gap (18)between the stationary housing (15) and the outermost annular chamber(9).